Low cost, connectorless, ruggedized small form factor optical sub-assembly (OSA) and data bus-in-A-box (BIB)

ABSTRACT

Systems, methods, and apparatus for an optical sub-assembly (OSA) are disclosed. In one or more embodiments, the disclosed apparatus involves a package body, and a lock nut, where a first end of the lock nut inserted into a first cavity of the package body. The apparatus further involves a transistor outline (TO) can, where a first end of the TO can is inserted into a second cavity of the package body. Also, the apparatus involves an optical fiber, where a portion of the jacket from an end of the optical fiber is stripped off, thereby exposing bare optical fiber at the end of the optical fiber. The end of the optical fiber is inserted into a second end of the lock nut such that the bare optical fiber passes into the package body and at least a portion of the bare optical fiber is inserted into the TO can cavity.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to U.S. patent application Ser. No.14/533,865, filed Nov. 5, 2014, titled Data Bus-in-a-Box (BiB) SystemDesign and Implementation, by Chan, et al.

FIELD

The present disclosure relates to optical sub-assemblies and data buses.In particular, it relates to a low cost, connectorless, ruggedized smallform factor optical sub-assembly (OSA) and data bus-in-a-box (BiB)design and assembly process.

BACKGROUND

Currently, some system data bus architectures (e.g., an ARINC plasticoptical fiber (POF) 629 data bus) employed in aircraft (e.g., a modernaircraft) require an individually packaged optical media converter (OMC)for each channel. They also require individually packaged passiveoptical star couplers. These individually packaged units areinterconnected together by fully jacketed aircraft POF cables that aresubjected to abuse during installation. The connectors required forthese packages are not only heavy, bulky, and costly, but also addsignificant optical attenuation to the system's optical power budget.The optical media converters (OMCs) and optical star couplers alsorequire custom designed support brackets and rails to mount them to theaircraft structure members. Each OMC (which contains a transmit (Tx)optical sub-assembly (OSA) and a receive (Rx) OSA) and optical starcoupler must be manufactured and tested individually, thereby incurringmuch more time and cost. When an OMC fails, an aircraft mechanic mustremove it and install a new OMC in its place, which requires additionaltime and cost. As such, there is a need for an improved data busarchitecture design.

SUMMARY

The present disclosure relates to a method, system, and apparatus for anoptical sub-assembly (OSA), which may be employed in the disclosed dataBiB design. In one or more embodiments, a method for manufacturing anoptical sub-assembly (OSA) involves inserting a first end of a lock nutinto a first cavity of a package body. The method further involvesinserting a first end of a transistor outline (TO) can into a secondcavity of the package body. Also, the method involves stripping aportion of a jacket from an end of an optical fiber (e.g., a plasticoptical fiber (POF)), thereby exposing bare optical fiber at the end ofthe optical fiber. Additionally, the method involves inserting the endof the optical fiber into a second end of the lock nut such that thebare optical fiber passes into the package body and at least a portionof the bare optical fiber inserts into a cavity of the TO can. Further,the method involves dispensing glue into a third cavity of the packagebody to environmentally seal the bare portion of the optical fiber.

In one or more embodiments, the TO can is a hermetically sealed TO can.

In at least one embodiment, the TO can comprises a lens.

In one or more embodiments, the OSA is tilted approximately thirty (30)degrees from a plane of a mounting surface for the OSA.

In at least one embodiment, the method further involves securing, withat least one screw, a bottom side of the OSA to a mounting surface of aboard by applying the screw(s) through an opening in the board into amounting screw hole on the bottom side of the OSA, thereby mounting theOSA to the board.

In one or more embodiments, the board is an optical media converter(OMC) printed circuit board (PCB).

In at least one embodiment, the OSA is an optical transmitter. In someother embodiments, the OSA is an optical receiver.

In one or more embodiments, the optical fiber (e.g., plastic opticalfiber), including the jacket, has a typical diameter of approximately2.2 millimeter (mm), and a diameter size down to approximately 1.5 mm isacceptable (i.e. the diameter ranges from approximately 1.5 mm toapproximately 2.2 mm). In some embodiments, the bare optical fiber(e.g., plastic optical fiber), without the jacket, has a diameter ofapproximately 1 millimeter (mm).

In at least one embodiment, the glue is a military specification(mil-spec) grade epoxy.

In one or more embodiments, the method further involves dispensing glueinto the second end of the lock nut to secure the lock nut to thepackage body.

In at least one embodiment, the method further involves manufacturingthe package body by molding the package body from a cool polymermaterial.

In one or more embodiments, an apparatus for an optical sub-assembly(OSA) involves a package body; and a lock nut, where a first end of thelock nut is inserted into a first cavity of the package body. Theapparatus further involves a transistor outline (TO) can, where a firstend of the TO can is inserted into a second cavity of the package body.Also, the apparatus involves an optical fiber (e.g., a plastic opticalfiber), where a portion of a jacket from an end of the optical fiber isstripped off, thereby exposing bare optical fiber at the end of theoptical fiber. In one or more embodiments, the end of the optical fiberis inserted into a second end of the lock nut such that the bare opticalfiber passes into the package body and at least a portion of the bareoptical fiber is inserted into a cavity of the TO can. In at least oneembodiment, glue is dispensed (e.g., inserted) into a third cavity ofthe package body, thereby environmentally sealing the bare optical fiber(e.g., the plastic optical fiber).

In at least one embodiment, the TO can is hermetically sealed.

In one or more embodiments, the package body is manufactured from amolded cool polymer material.

The features, functions, and advantages can be achieved independently invarious embodiments of the present disclosure or may be combined in yetother embodiments.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIGS. 1A and 1B are diagrams showing the disclosed optical sub-assembly(OSA) package body, in accordance with at least one embodiment of thepresent disclosure.

FIG. 2 is a diagram illustrating the assembly process of the disclosedOSA, in accordance with at least one embodiment of the presentdisclosure.

FIGS. 3A and 3B are additional diagrams illustrating the assemblyprocess of the disclosed OSA, in accordance with at least one embodimentof the present disclosure.

FIG. 4 is a flow chart of the disclosed method for manufacturing an OSA,in accordance with at least one embodiment of the present disclosure.

FIGS. 5A, 5B, and 5C are diagrams illustrating the transmit (Tx) opticalmedia converter (OMC) printed circuit board (PCB) design and assemblyprocess, in accordance with at least one embodiment of the presentdisclosure.

FIG. 6 is a diagram showing the assembly process of mounting a Tx OSA toa Tx OMC PCB, in accordance with at least one embodiment of the presentdisclosure.

FIGS. 7A and 7B are diagrams illustrating the assembly process of areceiver (Rx) OSA, in accordance with at least one embodiment of thepresent disclosure.

FIGS. 8A, 8B, and 8C are diagrams illustrating the Rx OMC PCB design andassembly process, in accordance with at least one embodiment of thepresent disclosure.

FIG. 9 is a diagram showing the assembly process of mounting a Rx OSA toa Rx OMC PCB, in accordance with at least one embodiment of the presentdisclosure.

FIG. 10 is a diagram showing the assembly of optical media converters(OMCs) (comprising Tx OMC portions and Rx OMC portions) mounted onto acopper core PCB mother board, in accordance with at least one embodimentof the present disclosure.

FIG. 11 is a diagram showing the details of a OMC (comprising a Tx OMCportion and an Rx OMC portion) mounted onto a copper core PCB motherboard, in accordance with at least one embodiment of the presentdisclosure.

FIG. 12 is a diagram showing the assembled PCB mother board insertedinto the back plane of a 3 MCU sized data bus-in-a-box (BiB), inaccordance with at least one embodiment of the present disclosure.

FIG. 13 is a diagram showing the details of the assembled PCB motherboard inserted into the back plane of a 3 MCU sized data bus-in-a-box(BiB), in accordance with at least one embodiment of the presentdisclosure.

FIG. 14 is a diagram showing the connections of plastic optical fiber(POF) from POF star couplers to the Tx OMC portions and the Rx OMCportions and to optical connectors on the side of the data BiB, inaccordance with at least one embodiment of the present disclosure.

FIG. 15 is a diagram illustrating an interior view of the data BiB afterfinal assembly, in accordance with at least one embodiment of thepresent disclosure.

DESCRIPTION

The methods and apparatus disclosed herein provide an operative systemfor a low cost, connectorless, ruggedized small form factor opticalsub-assembly (OSA) and data bus-in-a-box (BiB) design and assemblyprocess. The present disclosure involves the design and fabricationprocess of a tilted optical sub-assembly (OSA). The disclosed OSAprovides maximum space allocation for the electronic circuits on theprinted circuit board (PCB) (e.g., mother board) of the disclosed dataBiB design; while at the same time, maintains the optimum opticalperformance for both the transmitter and receiver to provide a minimumof a 54 decibels (dB) power budget required for the POF 629 system databus of a modern aircraft.

The disclosed OSA design uses a POF lock nut and a high precision, highthermal conductivity and electrically insulating, molded, cool polymerpackage body to embed the laser transmitter and receiver in ahermetically sealed transistor outline (TO) can package. The coolpolymer package body is precision molded to align a POF to the lasertransmitter and receiver passively, without labor intensive POF activealignment steps. Securing the lock nut together with using a mil-specgrade epoxy provides an environmental seal to the POF end face to thesurface of the TO can. The use of a POF lock nut eliminates the need forconnectors to couple the POF, thereby further reducing the assembly costfor the data BiB POF 629 system. The disclosed OSA design meets the lowcost, high performance, and stringent environmental requirements of thePOF 629 system data bus for aircraft production.

A POF 629 data system bus architecture for an exemplary modern aircraftrequires thirty (30) optical media converters (OMCs). The disclosed dataBiB design utilizes a 3 MCU sized box (i.e. 3.56 inches (″) width(W)×7.46″ height (H)×12.76″ depth (D)). As such, the 30 opticaltransmitters and receivers need to be incorporated into a small sizedbox (e.g., 3 MCU sized box). Since electronic circuits occupy most ofthe space on the PCB (e.g., mother board) of the BiB design, aconventional flat surface, fiber optic transceiver package form factoris too large to be incorporated onto the disclosed BiB PCB. To solvethis problem, each OMC employs a titled Rx OSA and a tilted Tx OSA. Thedisclosed tilted OSA design allows for packaging of the 30 OMCs into thesmall sized box of the disclosed data BiB.

The present disclosure presents the concept of replacing the copper buscables, the quad stub cables, the couplers, and the complex couplerpanel assembly of the ARINC 629 system bus that is currently employed inmodern airplanes with the disclosed POF 629 optical data BiB. The basicapproach of the POF 629 data BiB is to replace the current mode couplerdata bus with plastic optical fiber (POF), optical media converters(OMCs), and POF couplers (e.g., star couplers). The projected weightsavings by using the disclosed data BiB, instead of using a conventionalcopper ARINC 629 data bus, is over 100 pounds (lbs) per airplane, andthe projected cost savings is over $100K per airplane.

An exemplary modern aircraft system bus architecture connects up to 30line replaceable units (LRUs) in the front (or forward) section of theaircraft and connects 2 to 4 LRUs in the back (or aft) section of theairplane. To achieve a desired size, weight, power, and cost reductionfor the disclosed system data BiB design, the challenge was to packageand assemble 30 (e.g., 25 plus 5 spare) OMCs in a compact 3 MCU (or 4MCU) sized avionics box, while at the same time achieve high reliabilityand ruggedness that are required by the commercial avionics environment.The description of the figures below discusses the disclosed opticalsub-assembly (OSA) design and the assembly process for the discloseddata BiB. The OSA design and assembly process are the key to achievingthe desired size, weight, power, and cost reduction objectives for thePOF 629 system data bus in the modern airplane.

Each OMC in the data BiB is made up of a transmitter (Tx) PCB and areceiver (Rx) PCB. Each Tx and Rx PCB are approximately 2″ by 1″ indimensions, and are manufactured from two-sided copper core PCB to allowfor maximum space allocation for the electronics components, such asinductors, capacitors, resistors, and integrated circuit (IC) chips,which take up a large portion of the PCB space. As such, the design ofthe OSA needs to be compact and to be able to occupy a minimum space onthe PCB. Regarding the disclosed Tx OSA design, the Tx OSA houses alaser in a hermetically sealed transistor outline (TO) can, which needsto be precisely coupled to the POF to achieve maximum transmit outputpower. For the disclosed Rx OSA design, the Rx OSA houses a receiver ina hermetically sealed TO can with a lens cap, and the receiver TO canneeds to be precisely coupled to the POF to achieve maximum receiversensitivity. The disclosed Tx OSA and Rx OSA designs for the system busof the POF 629 architecture are able to assure (as required for thesystem data bus of some modern aircraft) a minimum of a 54 decibel (dB)power budget over the operating temperature range of −40° Celsius (C) to85° C., and at the same time maintain this performance over twenty (20)years of operating life time under stringent avionics environments, suchas high vibration, humidity, and contamination.

In the following description, numerous details are set forth in order toprovide a more thorough description of the system. It will be apparent,however, to one skilled in the art, that the disclosed system may bepracticed without these specific details. In the other instances, wellknown features have not been described in detail so as not tounnecessarily obscure the system.

Embodiments of the present disclosure may be described herein in termsof functional and/or logical block components and various processingsteps. It should be appreciated that such block components may berealized by any number of hardware, software, and/or firmware componentsconfigured to perform the specified functions. For example, anembodiment of the present disclosure may employ various integratedcircuit components, e.g., memory elements, digital signal processingelements, logic elements, look-up tables, or the like, which may carryout a variety of functions under the control of one or moremicroprocessors or other control devices. In addition, those skilled inthe art will appreciate that embodiments of the present disclosure maybe practiced in conjunction with, and that the system described hereinis merely one example embodiment of the present disclosure.

For the sake of brevity, conventional techniques and components relatedto optical sub-assemblies (OSAs) and data buses, and other functionalaspects of the system (and the individual operating components of thesystems) may not be described in detail herein. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent example functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in an embodiment of the present disclosure.

FIGS. 1A and 1B are diagrams showing the disclosed optical sub-assembly(OSA) package body 100, in accordance with at least one embodiment ofthe present disclosure. In particular, FIG. 1A shows the side view 110of a tilted Tx OSA package body 100, and FIG. 1B shows the bottom 120view of the tilted Tx OSA package body 100. The shape and dimensions ofthe OSA package body 100 are designed to accommodate a POF alignmentlock nut and a Tx laser diode TO can. As such, the OSA package body 100has a POF lock nut recess hole (e.g., a first cavity of the packagebody) 140 and a TO can recess hole (e.g., a second cavity of the packagebody) 130.

The OSA package body 100 is designed to have a 30 degrees tilt angle 150from the plane of the base 160 of the OSA package body 100 (e.g., fromthe plane of the mounting surface (or bottom surface) 160 of the OSApackage body 100). The OSA package body 100 is tilted to allow for morespace for electronic components on the Tx OMC PCB, without affecting theoptimum optical alignment position of the POF to the laser diode insidethe TO can.

The bottom side of the tilted Tx OSA package body 100 has two small (orone large) threaded holes 170 for securely mounting the Tx OSA packagebody 100 onto the Tx OMC PCB. The OSA package body 100 is made from acool poly material, which is a high thermal conductivity, non-conductingpolymer material. The OSA package body 100 is fabricated by a highvolume, low cost, precision molding process. The TO can and the POF locknut are inserted into the cavities 130, 140, respectively, of the OSApackage body 100, and attached to the OSA package body 100 by mil specgrade epoxy. The body has a POF glue hole (e.g., a third cavity of thepackage body) 180 in the middle to fill in mil spec grade epoxy forholding the POF in the groove hole 190 of OSA package body 100, and foralso providing an environmental seal of the bare portion of the POFinside the alignment groove 190.

FIG. 2 is a diagram 200 illustrating the assembly process of thedisclosed OSA, in accordance with at least one embodiment of the presentdisclosure. In particular, FIG. 2 shows a POF lock nut 210 and a laserTx TO can 220 to be inserted into the first cavity 140 and the secondcavity 130, respectively, of the OSA package body 100 of FIG. 1. Thelock nut 210 has a turning knob 230 for locking the POF inserted intothe OSA package body 100. The lock nut 210 has two rectangularanti-rotation flanges 240 located on two sides of the lock nut 210.

FIGS. 3A and 3B are additional diagrams 300, 310 illustrating theassembly process of the disclosed OSA, in accordance with at least oneembodiment of the present disclosure. In particular, FIG. 3A shows anassembled OSA 330 with a POF 320 ready to be inserted, and FIG. 3B showsthe POF 320 inserted into the assembled OSA 330 through the lock nut 210and fitted into the POF groove 190, where the POF 320 is alignedprecisely to the laser in the Tx TO can 220. The POF 320 has a corediameter 340 of about 1 millimeter (mm) and the jacketed diameter 350 ofabout 2.2 mm. The diameter of the POF groove 190 is designed to closelymatch the diameter of the POF core 340. The jacket of the POF 320 isstripped off a small section at the tip 360 to allow the core insertionin the POF groove 190. After insertion of the POF 320 into the OSApackage body 100, the knob 230 of the lock nut 210 is turned to securethe POF 320 to the OSA package body 100. Additionally, mil spec gradeepoxy is filled in the OSA body glue hole (e.g., the third cavity of thepackage body) 180 to permanently attach the POF 320 to the tilted OSApackage body 100. The epoxy also provides an environmental seal for aportion of the POF 340 and the TO can 220 interface. Epoxy canoptionally be added to the end 370 of the lock nut 210 to preventloosening of the knob 230 during operation of the data BiB. Theassembled OSA 330 requires no POF connector to mate with the Tx laser TOcan 220. This eliminates the cost associated with POF connectors, andalso eliminates the requirement for the space needed for the POFconnectors inside of the data BiB.

FIG. 4 is a flow chart of the disclosed method 400 for manufacturing anOSA, in accordance with at least one embodiment of the presentdisclosure. At the start 410 of the method 400, a first end of a locknut is inserted into (and glued to) a first cavity of a package body420. A first end of a transistor outline (TO) can is inserted into (andglued to) a second cavity of the package body 430. A portion of a jacketfrom an end of an optical fiber (e.g., plastic optical fiber) isstripped, thereby exposing a bare portion of the optical fiber at theend of the optical fiber 440. The end of the optical fiber (i.e. the endwith the exposed bare optical fiber) is inserted into a second end ofthe lock nut such that the bare optical fiber passes through the packagebody and at least a portion of the bare optical fiber (e.g., an end faceof the bare optical fiber) inserts into a cavity of the TO can 450. Glueis inserted (or dispensed) into a third cavity of the package body toenvironmentally seal the bare optical fiber 460. Then, the method ends.

FIGS. 5A, 5B, and 5C are diagrams illustrating the transmit (Tx) opticalmedia converter (OMC) printed circuit board (PCB) design and assemblyprocess, in accordance with at least one embodiment of the presentdisclosure. Specifically, FIG. 5A shows a Tx PCB (e.g., a 2″×1″ doublesided PCB with a copper core 540) 500 with two set of metal pins 510 a,510 b on its sides. These pins 510 a, 520 b may be pins of variousshapes (e.g., L-bend shaped, J-bend shaped, and/or straight pins) thatare compatible with the low cost and highly reliable PCB surfacemounting (SMT) processes. The PCB 500 has thermal via holes 520 thatconnect the set of the metal pins 510 b to the copper core 540 of thePCB 500 for thermal conduction and heat sinking to the mother board ofthe data BiB. Another set of electrically insulated metal pins 510 aconnects the signal and power lines of the Tx OMC PCB 500 to the BiBmother board. The PCB 500 also has a screw hole 530 for mounting a TxOSA onto the Tx PCB 500.

FIG. 5B shows electronic components 550 assembled (e.g., mounted) onboth sides of the Tx OMC PCB 500 by using, for example, SMT technology.FIG. 5C shows electromagnetic interference (EMI) protection metal lids560 assembled (e.g., mounted) on both the top and bottom sides of the TxPCB 500.

FIG. 6 is a diagram 600 showing the assembly process of mounting a TxOSA 330 (refer to FIGS. 3A and 3B) to a Tx OMC PCB 500 (refer to FIGS.5A, 5B, and 5C), in accordance with at least one embodiment of thepresent disclosure. In particular, FIG. 6 shows a tilted Tx OSA 330attached onto a Tx PCB 500, which, for example, is assembled as shown inFIG. 5. Before the Tx OSA 330 is mechanically attached to the Tx PCB500, mil spec grade, thermally conductive, epoxy is applied to thebottom side 160 of the Tx OSA 330. Then, the Tx OSA 330 is attached tothe Tx PCB 500 via a mounting screw 610 placed into the pre-mademounting hole 530 on the Tx PCB 500. After the epoxy has cured, the TxOSA 330 is permanently attached to the surface the Tx PCB 500. Becauseof the tilting of the POF in the Tx OSA 330, the POF fiber and the locknut 210 are not taking any space on the Tx PCB 500, thereby leaving alot of extra area for mounting electronic components onto the Tx PCB500.

FIGS. 7A and 7B are diagrams 700, 710 illustrating the assembly processof a receiver (Rx) OSA, in accordance with at least one embodiment ofthe present disclosure. Specifically, FIGS. 7A and 7B show a tilted RxOSA 735 design, which is similar to the Tx OSA 330 design described inFIGS. 3A and 3B. In particular, FIG. 7B shows an assembled Rx OSA 735ready for POF insertion, and FIG. 7A shows a lock nut 210 ready to beinserted into a POF lock nut recess hole (e.g., a first cavity of thepackage body) 740 in the Rx OSA package body 705.

The Rx OSA package body 705 houses the Rx TO can 720, which has a lenscap 725. The size of the recess region (e.g., a second cavity of thepackage body) 730 of Rx OSA package body 705 has to precisely fit the RxTO can 720 and to center the lens of the TO can 720 at an optimumdistance from the center of the end face of the POF. This distance iscrucial to achieve over −34 decibel-milliwatts (dBm) or higher receiversensitivity for the Rx OMC.

The OSA package body 705 is designed to have a 30 degrees tilt angle 750from the plane of the base 760 of the OSA package body 705 (e.g., fromthe plane of the mounting surface (or bottom surface) 760 of the OSApackage body 705). The OSA package body 705 is tilted to allow for morespace for electronic components on the Rx OMC PCB, without affecting theoptimum optical alignment position of the POF to the detector inside theTO can.

The bottom side of the tilted Rx OSA package body 705 has two small (orone large) threaded holes 770 for securely mounting the Rx OSA packagebody 705 onto the Rx OMC PCB. The OSA package body 705 is made from acool poly material, which is a high thermal conductivity, non-conductingpolymer material. The OSA package body 705 is fabricated by a highvolume, low cost, precision molding process.

A POF (not shown) is to be inserted into the assembled Rx OSA 735through the lock nut 210 and fitted into the POF groove 790, where thePOF is aligned precisely to the detector in the Rx TO can 220. The POFhas a core diameter of about 1 millimeter (mm) and the jacketed diameterof about 2.2 mm. The diameter of the POF groove 190 is designed toclosely match the diameter of the POF core. The jacket of the POF isstripped off a small section at the tip to allow the core insertion inthe POF groove 190. After insertion of the POF into the OSA package body705, the knob 230 of the lock nut 210 is turned to secure the POF to theOSA package body 705. Additionally, mil spec grade epoxy is filled inthe OSA body glue hole (e.g., the third cavity of the package body) 780to permanently attach the POF to the tilted OSA package body 705. Theepoxy also provides an environmental seal for the POF and TO can 720interface. Epoxy can optionally be added to the end 370 of the lock nut210 to prevent loosening of the knob 230 during operation of the dataBiB. The assembled OSA 735 requires no POF connector to mate with the Rxdetector TO can 720. This eliminates the cost associated with POFconnectors, and also eliminates the requirement for the space needed forthe POF connectors inside of the data BiB.

FIGS. 8A, 8B, and 8C are diagrams illustrating the Rx OMC PCB design andassembly process, in accordance with at least one embodiment of thepresent disclosure. In particular, FIGS. 8A, 8B, and 8C show the Rx OMCPCB design and assembly process, which are similar to the Tx OMC PCBassembly process shown in FIGS. 5A, 5B, and 5C; except for FIGS. 8A, 8B,and 8C, the electronic components are selected for use with the Rx OMC.

Specifically, FIG. 8A shows a Rx PCB (e.g., a 2″×1″ double sided PCBwith copper core 840) 800 with two set of metal pins 810 a, 810 b on itssides. Pins 810 a, 820 b may be pins of various shapes (e.g., L-bendshaped, J-bend shaped, and/or straight pins) that are compatible withthe low cost and highly reliable PCB surface mounting (SMT) processes.The PCB 800 has thermal via holes 820 that connect the set of the metalpins 810 b to the copper core 840 of the PCB 800 for thermal conductionand heat sinking to the mother board of the data BiB. Another set ofelectrically insulated metal pins 810 a connects the signal and powerlines of the Rx OMC PCB 800 to the BiB mother board. The PCB 800 alsoincludes a screw hole 830 for mounting a Rx OSA onto the Rx PCB 800.

FIG. 8B shows electronic components 850 assembled on both sides of theRx OMC PCB 800 by using, for example, SMT technology. FIG. 8C showselectromagnetic interference (EMI) protection metal lids 860 assembledon both the top and bottom sides of the Rx PCB 800.

FIG. 9 is a diagram showing the assembly process of mounting an Rx OSA735 to a Rx OMC PCB 800, in accordance with at least one embodiment ofthe present disclosure. Specifically, FIG. 9 shows an Rx OMC PCBassembly 735 with a tilted Rx OSA package body 705 attached to a Rx OMCPCB 800 by using the same process steps for the Tx OSA 330 as describedin FIG. 6. The tilted Rx OSA's fiber lock nut 210 does not occupy anyspace on the Rx PCB 800 and, as such, this provides the maximum spaceallocation for the electronic components on the Rx PCB 800.

In particular, FIG. 9 shows a tilted Rx OSA 735 attached onto an Rx PCB800, which, for example, is assembled as shown in FIGS. 7A and 7B.Before the Rx OSA 735 is mechanically attached to the Rx PCB 800, milspec grade epoxy is applied to the bottom side 760 of the Rx OSA 735.Then, the Rx OSA 735 is attached to the Rx PCB 800 via a mounting screw910 placed into the pre-made mounting hole 830 on the Rx PCB 800. Afterthe epoxy has cured, the Rx OSA 735 is permanently attached to thesurface the Rx PCB 800.

FIG. 10 is a diagram 1000 showing the assembly of optical mediaconverters (OMCs) 1010 (comprising Tx OMC portions 1020 and Rx OMCportions 1030) mounted onto a copper core PCB mother board 1040, inaccordance with at least one embodiment of the present disclosure. Inparticular, FIG. 10 shows the top view of one (1) row of Tx OMC portions1020 of an OMC 1010 and 1 row of Rx OMC portions 1030 of an OMC 1010attached to a 12.5″ width (W) by 7″ height (H) PCB mother board 1040 ofthe data BiB. The details of a single OMC 1010 will be described indetail in the description of FIG. 11.

FIG. 11 is a diagram showing the details of a OMC (comprising a Tx OMCportion 1020 and an Rx OMC portion 1030) 1010 mounted onto a copper core1100 PCB mother board 1040, in accordance with at least one embodimentof the present disclosure. As shown in FIG. 11, the data BiB motherboard 1040 is a two-sided PCB with a thick copper core 1100 for maximumthermal heat sinking of the Tx OMC PCB 500 and the Rx OMC PCB 800 to thedata BiB back plane (refer to 1210 of FIG. 12). The mother board 1040has thermal via holes 1110 to connect the Tx OMC thermal pins 510 b andthe Rx OMC thermal pins 810 b to the copper core 1100 of the motherboard 1040.

The mother board 1040 also has signal via hole 1120 for connecting thesignal (e.g. by using a signal wire) from the Tx OMC PCB 500 to the RxOMC PCB 800, and vice versa. An under filling process is used to addthermal conductive and electrical insulating epoxy between the bottom ofthe Tx OMC PCB 500 and the mother board 1040 for mechanical strengthenhancement and heat sinking of Tx OMC PCB 500 to the mother board 1040.In addition, an under filling process is used to add thermal conductiveand electrical insulating epoxy between the bottom of the Rx OMC PCB 800and the mother board 1040 for mechanical strength enhancement and heatsinking of Rx OMC PCB 800 to the mother board 1040.

Referring back to FIG. 10, the mother board 1040 is designed such thatone side will have all Rx OMC portions 1030 and the opposite side willhave all Tx OMC portions 1020. This way, the connections of the POF tothe Rx OMC portions 1030 and the connections of the POF to the Tx OMCportions 1020 will not need to cross over the mother board 1040 in themiddle of the data BIB. This feature will be more clearly shown in FIG.14. The mother board 1040 for the disclosed data BiB accommodates 30(i.e. 5 columns×6 rows) Tx OMC portions 1020 on one side and 30 (i.e. 5columns×6 rows) Rx OMC portions 1030 on the opposite side. This allowsfor a total of 30 OMCs 1010 with full Tx and Rx operation on a singlemother board 1040. An alternative arrangement of 3 columns×10 rows OMCportions on each side of the mother board 1040 is also acceptable forthe disclosed data BiB design.

FIG. 12 is a diagram 1200 showing the assembled PCB mother board 1040inserted into the back plane 1210 of a 3 MCU sized data bus-in-a-box(BiB) 1220, in accordance with at least one embodiment of the presentdisclosure. In particular, FIG. 12 shows the completely populated motherboard 1040 inserted into the backplane 1210 of a 3 MCU sized data BiB1220 with a width (W) of 3.56″ and a depth (D) of 12.76″ and a height(H) of 7.64″. It should be noted that 4 MCU sized data BiB with a 4.88″width is an acceptable alternative size, if the airplane spaceallocation is permitted. Section 1230 of FIG. 12 will be described indetail in the description of FIG. 13.

FIG. 13 is a diagram 1230 showing the details of the assembled PCBmother board 1040 inserted into the back plane 1210 of a 3 MCU sizeddata BiB 1220, in accordance with at least one embodiment of the presentdisclosure. In this figure, the mother board 1040 is inserted into aback plane connector 1300 to connect to, via power and signal electricaltraces 1330, the power and signal pins 1310 of the LRU connectors 1320at the back of the data BiB 1220. A guide rail (not shown) on a top andbottom edge of the mother board 1040 is used to guide and align themother board 1040 to the back plane connector 1300. The data BiB backplane 1210 has a back plane PCB 1350 with a thermal conduction backlayer 1340, which is attached to the back wall of the data BiB 1220.This thermal conduction back layer 1340 may be a metal plate or a thickcopper layer on the back of the back plane PCB 1350. The copper core1100 of the PCB mother board 1040 is connected to the thermal conductionback layer 1340 of the back plane PCB 1350 to conduct heat away from theTx OMC PCB 500 and the Rx OMC PCB 800 to the back side of the data BiB1220. The back of the data BiB 1220 is externally cooled by a convectionair flow system in the airplane. The air flow capacity is thermallydesigned to remove heat efficiently away from the Tx OMC PCB 500 and theRx OMC PCB 800.

There are six LRU electrical connectors 1320 mounted to the data BiB viaelectrical connector mounting flanges 1360. Each electrical connector1320 provides minimum of twenty-four (24) electrical pins 1310 toconnect with six OMCs 1010. As such, five electrical connectors 1320 areused to connect the 30 OMCs 1010 with 30 LRUs in an exemplary modernaircraft system bus. There is one optical connector (not shown) that isused to connect the front data BiB 1220 (located in the front of theaircraft) to the back data BiB, which is similar in design to the frontdata BiB 1220 but has fewer OMC, (located in the back of the aircraft)for the modern aircraft system data bus via two POF cables, which areeach 60 meters in length.

FIG. 13 shows a top view of the data BiB back plane 1210 with theelectrical connector 1320 locations. An optical connector (not shown)would be located below the electrical connectors 1320 on the data BiB1220. The data BiB back plane PCB 1350 is multi-layer structure withembedded power and signal electrical traces 1330 to connect the metalpins 1310 of the electrical connectors 1320 to the mother board 1040,which is connected to all of the fully assembled OMCs 1010. The motherboard 1040 has metal pads on its edge to connect with the back plane's1210 embedded metal traces 1330.

The alternative approach for connection of the data BiB 1220 motherboard 1040 to the electrical connectors 1320 is by using a flexible(flex) circuit. This would be an acceptable approach if the thermalconductivity as well as the material and fabrication cost are compatiblewith using a back plane connector 1210.

FIG. 14 is a diagram 1400 showing the connections of POF cables 1410 a,1410 b, 1410 c, 1410 d from POF star couplers 1420 a, 1420 b to the TxOMC portions 1020 and the Rx OMC portions 1030 and to optical connectors1430 on the side of the data BiB 1220, in accordance with at least oneembodiment of the present disclosure. In particular, FIG. 14 shows thedetails of the POF 1410 a, 1410 b, 1410 c, 1410 d connections of the POFstar couplers 1420 a, 1420 b to the tilted OSAs 330, 735. The POF starcouplers 1420 a, 1420 b are each a tapered dual-star-in-one design. POFstar coupler 1420 a uses POF 1410 a to connect to all of the Tx OSAportions 1020 on one side of the mother board 1040, and POF star coupler1420 b uses POF 1410 b to connect to all of the Rx OSA portions 1030 onthe opposite side of the mother board 1040. This data BiB 1220 OMC 1010layout prevents the POF 1410 a, 1410 b from needing to cross over themother board 1040. It should be noted that a mother board design with TxOMC portions and Rx OMC portions co-located on the same side of themother board would require the POF to cross-over the mother board inorder to fully connect all the OMCs to the POF star couplers.

POF 1410 c, 1410 d are used to connect the POF star couplers 1420 a,1420 b to an optical connector (not shown) located on the back side ofthe data BiB 1220. These POF 1410 c, 1410 d are used to connect the dataBiB 1220 located in the back section of the modern aircraft system databus. The data BiB located in the back section of the modern aircraftalso has a POF star coupler 1410 that connects with a minimum of twoOMCs 1010 at the back section of the airplane. The design andfabrication process of the data BiB 1220 located in the back of theairplane will be similar to the data BiB 1220 located in the front ofthe airplane, except the back data BiB 1220 will employ a smaller sizedbox than the front data BiB 1220. After the POF connections 1410 a, 1410b, 1410 c, 1410 d to the POF star couplers 1420 a, 1420 b have beencompleted and tested, a light weight, thermally conductive andelectrically insulating foam material 1430 is used to fill in the spacebetween the mother board 1040 and the side walls of the data BiB 1020.The foam material 1430 adds an additional thermal conduction path forthe Tx OMC PCB 500 to the data BiB 1220 side wall and for the Rx OMC PCB800 to the data BiB 1220 side wall.

FIG. 15 is a diagram 1500 illustrating an interior view of the data BiB1220 after final assembly, in accordance with at least one embodiment ofthe present disclosure. Specifically, FIG. 15 shows a schematic threedimensional (3D) conceptual view of the data BiB 1220 with 30 OMCs 1010and a dual POF star coupler 1420 a, 1420 b. The POF dual star coupler1420 a, 1420 b is shown in FIG. 15 to be mounted to the front side ofthe data BiB 1220. In alternative embodiments, the POF dual star coupler1420 a, 1420 b may be mounted on the bottom side or the top side of thedata BiB 1220 without a POF 1410 a, 1410 b, 1410 c, 1410 d cross overproblem. Status indicator light emitting diodes (LEDs) (not shown) canbe added to the back (or the front) side of the data BiB 1220 near theelectrical connectors 1310 to indicate the operation status of the OMCs1010 inside of the data BiB 1220. The OMCs 1010 (i.e. OMC PCB tiles)shown in FIG. 15 have a three (3) by (×) ten (10) tile format on eachside of the mother board 1040. The approach and assembly process of thepresent disclosure is the same for both a 3×10 OMC PCB tile 1010 formatand a five (5)×six (6) OMC PCB tile 1010 format on the mother board 1040of the data BiB 1020. The overall disclosed data BiB 1020 design andassembly process is able to achieve optimum optical, thermal, andmechanical performance. The disclosed design provides a data BiB 1020design with size, weight, power, and cost reduction for the a modernaircraft POF 629 system data bus architecture.

Although particular embodiments have been shown and described, it shouldbe understood that the above discussion is not intended to limit thescope of these embodiments. While embodiments and variations of the manyaspects of the present disclosure have been disclosed and describedherein, such disclosure is provided for purposes of explanation andillustration only. Thus, various changes and modifications may be madewithout departing from the scope of the claims.

Where methods described above indicate certain events occurring incertain order, those of ordinary skill in the art having the benefit ofthis disclosure would recognize that the ordering may be modified andthat such modifications are in accordance with the variations of thepresent disclosure. Additionally, parts of methods may be performedconcurrently in a parallel process when possible, as well as performedsequentially. In addition, more parts or less part of the methods may beperformed.

Accordingly, embodiments are intended to exemplify alternatives,modifications, and equivalents that may fall within the scope of theclaims.

Although certain illustrative embodiments and methods have beendisclosed herein, it can be apparent from the foregoing disclosure tothose skilled in the art that variations and modifications of suchembodiments and methods can be made without departing from the truespirit and scope of the art disclosed. Many other examples of the artdisclosed exist, each differing from others in matters of detail only.Accordingly, it is intended that the art disclosed shall be limited onlyto the extent required by the appended claims and the rules andprinciples of applicable law.

We claim:
 1. A method for manufacturing an optical sub-assembly (OSA),the method comprising: inserting a first end of a lock nut into a firstcavity of a package body; inserting a first end of a transistor outline(TO) can into a second cavity of the package body; stripping a portionof a jacket from an end of an optical fiber, thereby exposing bareoptical fiber at the end of the optical fiber; inserting the end of theoptical fiber into a second end of the lock nut such that the bareoptical fiber passes into the package body and at least a portion of thebare optical fiber inserts into a cavity of the TO can; and dispensingglue into a third cavity of the package body to environmentally seal thebare optical fiber.
 2. The method of claim 1, wherein the TO can is ahermetically sealed TO can.
 3. The method of claim 1, wherein the TO cancomprises a lens.
 4. The method of claim 1, wherein the OSA is tiltedapproximately thirty (30) degrees from a plane of a mounting surface forthe OSA.
 5. The method of claim 1, wherein the method further comprises:securing, with at least one screw, a bottom side of the OSA to amounting surface of a board by screwing the at least one screw throughan opening in the board into a mounting screw hole on the bottom side ofthe OSA, thereby mounting the OSA to the board.
 6. The method of claim5, wherein the board is an optical media converter (OMC) printed circuitboard (PCB).
 7. The method of claim 1, wherein the OSA is an opticaltransmitter.
 8. The method of claim 1, wherein the OSA is an opticalreceiver.
 9. The method of claim 1, wherein the optical fiber, includingthe jacket, has a diameter of approximately 1.5 millimeters (mm) toapproximately 2.2 mm.
 10. The method of claim 1, wherein the bareoptical fiber, without the jacket, has a diameter of approximately 1millimeter (mm).
 11. The method of claim 1, wherein the glue is amilitary specification (mil-spec) grade epoxy.
 12. The method of claim1, wherein the method further comprises inserting glue into the secondend of the lock nut to secure the lock nut to the package body.
 13. Themethod of claim 1, wherein the method further comprises manufacturingthe package body by molding the package body from a cool polymermaterial.
 14. An apparatus for an optical sub-assembly (OSA), theapparatus comprising: a package body; a lock nut, wherein a first end ofthe lock nut is inserted into a first cavity of the package body; atransistor outline (TO) can, wherein a first end of the TO can isinserted into a second cavity of the package body; and an optical fiber,wherein a portion of a jacket from an end of the optical fiber isstripped off, thereby exposing bare optical fiber at the end of theoptical fiber, wherein the end of the optical fiber is inserted into asecond end of the lock nut such that the bare optical fiber passes intothe package body and at least a portion of the bare optical fiber isinserted into a cavity of the TO can, and wherein glue is dispensed intoa third cavity of the package body, thereby environmentally sealing thebare optical fiber.
 15. The apparatus of claim 14, wherein the TO can ishermetically sealed.
 16. The apparatus of claim 14, wherein the TO cancomprises a lens.
 17. The apparatus of claim 14, wherein the OSA istilted approximately thirty (30) degrees from a plane of a mountingsurface for the OSA.
 18. The apparatus of claim 14, wherein the OSA isan optical transmitter.
 19. The apparatus of claim 14, wherein the OSAis an optical receiver.
 20. The apparatus of claim 14, wherein thepackage body is manufactured from a molded cool polymer material.